JP2009-222136A issued by the Japan Patent Office in 2009 discloses a damping valve of a hydraulic damper including a poppet valve body.
The hydraulic damper comprises an outer tube outside a cylinder and a reservoir for working oil is formed in the outer tube outside the cylinder. A piston joined to a piston rod is housed in the cylinder. An oil chamber at the piston rod side and an oil chamber at an opposite side of the piston to the piston rod are delimited by the piston inside the cylinder.
The damping valve is provided in an oil passage for allowing the working oil to flow from the oil chamber at the piston rod side to the reservoir.
The leading end of a poppet forming the valve body is seated on a ring-shaped valve seat around a hole formed in the oil passage by a magnetic force of an excited solenoid, thereby closing the oil passage. In a state where the solenoid is not excited, the poppet is lifted from the valve seat and the working oil is allowed to flow via an annular clearance between the valve seat and the poppet.
When a pressure in the oil passage applied to the poppet increases in the state where the solenoid is excited, the leading end of the poppet is lifted from the valve seat against the magnetic force of the solenoid according to the pressure in the oil passage. As a result, the working oil flows into a valve chamber formed around the leading end of the poppet through the annular clearance formed between the valve seat and the leading end of the poppet. The valve chamber is formed with an outlet port for allowing the working oil to flow in a direction perpendicular to the leading end of the poppet, and the working oil flowed into the valve chamber from the oil passage flows out to the reservoir through the outlet port.
To support the poppet so as to be free to slide in an axial direction, the poppet comprises a base end formed to have a larger diameter than the leading end of the same. The base end of the poppet is fitted in a valve housing so as to be free to slide.